1. Field of the Invention
The present invention relates to a method for packaging a chip and a chip package assembly produced thereby, and particularly relates to a method that is rather than conventional package technologies and can improve the ability of packaging an optical electronic sensor, for example, the optical electronic sensor connects a predetermined region of a circuit layout of a transparent sheet via a conductive material, in order to form an unoccupied layer therebetween. After each chip is packaged, the transparent sheet is sawed into plurality of dices, the dices can be assembled into various camera module.
2. Description of Related Art
As much progress of electronic products does, such as being lightweight, thin, short and small, and being multiple functions, component packages applied for these electronic products develop with high frequency, quantities of I/O ports and microminiaturize. How to increase the production mass of and how to keep the quality of the component packages are the current issues.
With respect to FIGS. 1A and 1B, an optical electronic sensor package processed by the first conventional package method, a chip scale package (CSP) technology, is disclosed. A substrate 10a is prepared firstly. Secondly, a chip 20a with a micro-lens (μ-lens) array 21a is settled on the substrate, and a conductive pad 22a is arranged on the chip 20a and at the same top surface with the μ-lens array 21a. Thirdly, a terminal wrapping lead 30a is arranged from the conductive pad 22a of the chip 20a to a bottom of the substrate 10a. Fourthly, the bottom of the substrate 10a is dispensed with a solder ball array 11a, which electrically connects the conductive pad 22a via the terminal wrapping lead 30a. Fifthly, an optical paste 50a is coated on the chip 20a in order to stick with a cover glass 40a; a CSP device 1a is thus finally finished. During the post-processes, the CSP device 1a can be secured on to a printed circuit board 70a (a flexible board or a generic rigid board) by a reflow procedure during which the solder ball array 11a will melt for connecting therebetween, and a lens holder 60a, a lens 90a and an infrared ray filter 80a are gathered together on the printed circuit board 70a in sequence as a camera module (in FIG. 1B). As we know, the refraction index of the conventional cover glass 40a is about 1.6, the refraction index of the optical paste 50a is about 1.5, and the refraction index of the μ-lens array 21a is about 1.6. However, the optical paste 50a is filled between the chip 20a and the cover glass 40a, according to Snell's Law, the light passes through the cover glass 40 and is transmitted into the μ-lens array 21a via the optical paste 50a, and the CSP device 1a fails to provide good light convergence capacity and the image sensitivity of the camera module is bad. In addition, the CSP device 1a is obviously difficult to manufacture due to the complicated structure per se and the complex steps, the yield rate cannot raise so that the materials and the cost cannot be saved.
Referring to FIGS. 2A and 2B, an optical electronic sensor package processed by the second conventional package method, a chip on board (COB) technology, is disclosed. Firstly, a chip 20b is disposed on a printed circuit board 70b (generally a rigid board, or a flexible board also can be used), and a μ-lens array 21b and a conductive pad 22b are arranged at the same surface of the chip 20b. Secondly, a golden wire 30b bonds the conductive pad 22b to the printed circuit board 70b for the electrical connection. Thirdly, a lens holder 60b, a lens 90b and an infrared ray filter 80b are gathered together on the printed circuit board 70b in sequence, and further to seal this COB device 1b as a camera module for directly packaging, wherein the infrared ray filter 80b is arranged inside the lens holder 60b, the lens holder 60b is adhered to the printed circuit board 70b in advance, and the lens 90b is assembled into the lens holder 60b (in FIG. 2B). This camera module can be applied for electronic products hereafter. During the COB method, if there is any particle or dust fallen on the μ-lens array 21b of the chip 20b, a kind of critical failure mode will damage the image sensing, the fallen particle cannot be removed by any cleaning means, and therefore, the camera module absolutely fails. Thus, for keeping the COB device 1b from the particles and dusts, the whole process will be practiced in a clean room with high criteria, for example, a class 10 clean room in order to increase the yield rate. But such the clean room is so expensive, and the lager size of the clean room for containing all the equipments used in the COB processes costs more than the regular one. Furthermore, in the clean room, the airflow therein should be kept steady and stable, or the disturbed air and the induced particles will affect the yield rate. Nevertheless, the wire bonding procedure causes the air disturbance due to the high speed thereof.
Hence, an improvement over the prior art is required to overcome the disadvantages thereof.